B1 ~ Revision

• A balanced diet includes everything that is needed to keep the body healthy (TYPES OF FOOD) e.g. Mineral ions, vitamins, carbohydrates,fats and proteins.
• If someone's diet is unbalanced they can become malnourished. 
• If you excercise, more energy is used by the body. Excercise increases the METABOLIC RATE which means that the chemicall reactions in cells work faster
• If the energy (food) taken in is less than the energy used the person will lose mass.
• The more excercise you do the more food you need. 
• INHERITED factors also affect the metabolic rate.

• Eating too much food can lead to someone becoming OVERWEIGHT and OBESE.

• Long-term obesity can lead to severe health problems such as Type 2 DIABETES.(High Blood Preassure)

• Can be reduced by eating less carbohydrates and increasing the amount of excercise.

• Some people are unhealthy because they eat too little (STARVATION). These people might find it hard to walk and suffer from deficiency diseases due to lack of vitamins and minerals.

• As said previously metabolic rate can be INHERITED from your parents. 

• Two types of cholesterol good and bad.

• 'GOOD' CHOLESTEROL for your cell membranes and to make vital substances.

• A small amount of the population inherit 'BAD' CHOLESTEROL which can lead to HEART DISEASE.

• Foods rich in saturated fats can increase blood cholesterol levels.

• By exercising regularly a person can increase their metabolic rate and lower high cholesterol levels.

• PATHOGENS cause INFECTIOUS DISEASES.

• Pathogens are tiny MICROORGANISMS- ususally BACTERIA or VIRUSES.

• When bacteria or viruses enter the body they reproduce rapidly which makes us feel ill by producing TOXINS (poisons).

• Viruses are much smaller than bacteria and reproduce inside of cells. The damage to cells also makes you ill.

• SEMMELWEISS was the first to realise that infection could be transferred from person to person in a hospital. He told his staff to wash their hands between treating patients.

• The skin prevents pathogens getting into the body.

• Pathogens are also trapped by mucus and killed by stomach acid.

• WHITE BLOOD CELLS are part of the IMMUNE SYSTEM. They do 3 things to defend the body.

• INGEST pathogens (DIGEST and DESTROY)

• Produce ANTIBODIES to help destroy particular pathogens.

• Produce ANTITOXINS to get rid of the toxins that pathogens produce.

• ANTIBIOTICS kill infective bacteria in the body.

• Some medicines may relieve the symptoms but not kill the pathogens e.g painkillers.

• Viruses are difficult to kill because they reproduce in the body cells .

• Your immune system will usually overcome the ciral pathogen.

• Bacteria can be grown on AGAR JELLY. It must be pure cultures of non-pathogenic (safe) bacteria.
• Uncontaminated culture of microorganisms can be used to find the effect of of antibiotics on bacteria.
• Contamination might come from your skin, the air, the soil or the water around you.
• If the culture becomes contaminated then other bacteria might grow this includes pathogens.

To grow microorganisms in a laboratory you must:

• Give them a jell containing nutrients- a culture medium (Agar jelly is used).
• Provide warmth+ oxygen.
• Keep them incubated at 25°C in school laboratories.

To keep the cultures PURE:

• Kill all the bacteria on the equipment
• Prevent microorganisms from air getting into the equipment

• Some pathogens particularly viruses can MUTATE(change).
• Very few people are immune to these changed pathogens so diseases can spread quickly.

• Diseases that spread within the country result in an EPIDEMIC.
• Diseases that spread across countries result in a PANDEMIC.

• Some bacteria have developed resistance to antibiotics by natural selection. This is called MRSA which is the 'super bug'.

• Mutations of pathogens produce new strains which are resisitant to antibiotics.
• The resistant bacteria survive and reproduce. This is natural selection.
• Antibiotics should not be used for mild infections in order to prevent the rate of resisitant strains developing.

• Dead or inactive forms of pathogens are used for VACCINES.

• The White Blood Cells react by producing ANTIBODIES.

• This makes the person IMMUNE. It prevents further infections because the body responds quickly by producing more antibodies.

• The antibodies recognise the ANTIGEN (protein shape) on the pathogen.

• The MMR vaccination (immunisation) is one of the several vaccines. This is given to prevent Measles, mumps and rubella.

• Get vaccinated to prevent serious diseases.This protects individuals as well as society.

• Diseases such as measles can lead to long term damage to the body, such as deafness and occasionally death.

• Some vaccines cause side effects which may be mild or serious.

• Overuse of antibiotics can lead to the development of of new strains or bacteria.

• Doctors do not prescribe medicines for mild infections such as sore throats.